Indian Ocean

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Contents 1 INDIAN OCEAN CRUISING GUIDE 1.1 The Region 1.2 Indian Ocean Countries 1.3 Indian Ocean Islands 1.4 Indian Ocean Transits 1.5 Radio Nets 1.6 Weather 1.7 Charts 1.8 References 1.9 Forum Discussions 1.10 External Links 1.11 Personal Notes 2 Page Navigation

INDIAN OCEAN CRUISING GUIDE

An online cruising guide for sailing the Indian Ocean.

The Region

The Indian Ocean is the third largest of the world's oceanic divisions, covering about 20% of the water on the Earth's surface. It is bounded on the north by Asia (including the Indian subcontinent, after which it is named); on the west by Africa; on the east by Indochina, the Sunda Islands, and Australia; and on the south by the Southern Ocean (or, traditionally, by Antarctica). One component of the all-encompassing World Ocean, the Indian Ocean is delineated from the Atlantic Ocean by the 20° east meridian running south from Cape Agulhas, and from the Pacific by the 147° east meridian. The northernmost extent of the Indian Ocean is approximately 30° north in the Persian Gulf and, thus, has asymmetric ocean circulation. This ocean is nearly 10,000 kilometres (6,200 mi) wide at the southern tips of Africa and Australia; its area is 73,556,000 square kilometres (32.1 mi), including the Red Sea and the Persian Gulf.

The ocean's volume is estimated to be 292,131,000 cubic kilometers (70,086,000 mi³). Small islands dot the continental rims. Island nations within the ocean are Madagascar (formerly Malagasy Republic), the world's fourth largest island; Comoros; Seychelles; Maldives; Mauritius; and Sri Lanka. Indonesia borders it on the east. The ocean's importance as a transit route between Asia and Africa has made it a scene of conflict. Because of its size, however, no nation had successfully dominated most of it until the early 1800s when the United Kingdom controlled much of the surrounding land. After the decline of the British Empire, the ocean has since been dominated by India and Australia. Also see Wikipedia

Indian Ocean Countries

• Australia
• Indonesia
• Thailand
• Burma
• Sri Lanka
• South India
• Somalia
• Kenya
• Tanzania
• Mozambique
• South Africa

Indian Ocean Islands

• Christmas Island
• Cocos-Keeling
• Maldives
• Chagos Archipelago
• Zanzibar
• Seychelles
• Comoros
• Mayotte
• Madagascar
• Rodrigues
• Mauritius
• Reunion

Indian Ocean Transits

Also see the Mozambique Channel

• Southern Indian Ocean Crossing East to West
• Southern Indian Ocean Crossing West to East
• SE Asia to Red Sea
• Red Sea to SE Asia

Radio Nets

Also see World Cruiser's Nets

• South Africa Maritime Mobile Net - See Cruiser's Nets for details
• Radio Peri-Peri - See Cruiser's Nets for details
• Maritime Mobile Net South East Asia (MMNETSEA) - See Cruiser's Nets for details

Weather

WINDS & CURRENTS

NORTHERN INDIAN OCEAN
This area is generally dominated by the NE and SW monsoons, which refers to the directions of the prevailing winds.

The NE monsoon is the cooler season and is mostly dry, whereas the SW monsoon is known as the rainy season, often with torrential rain and hot, humid conditions.

The SW Monsoon blows during the northern summer, from about May to September/October. The influence of this stretches across the northern Indian Ocean, from the Gulf of Aden to the Andaman Sea, often with force 7 - 8 winds, for days on end. This wind direction can be used to ones advantage, in a passage from the Maldives or Sri Lanka to Thailand or Malaysia.

The Northeast Monsoon blows during the northern winter from about November to March. The NE monsoon blows with less consistency than its opponent wind and covers the same area, and is generally of lighter force, 4 - 5 being the norm. Early in the year is the recommended time for making a westerly passage across the northern Indian Ocean. The ocean currents mostly follow the direction of the prevailing monsoons and are mostly in the ½ to 1 knot range. In the northern winter the equatorial current is almost non-existent.

SOUTHERN INDIAN OCEAN
The southern Indian Ocean, from around 4ºS to 25ºS, is dominated all year round by the SE Trade Winds. In the Mozambique Channel the wind direction can change and is often higher than the average force 4 – 5 of the SE Trades. The recommended time to use these trades to your advantage is between mid April and mid November. South of the Equator there is a W to SW current, the South Equatorial Current, of around ½ to 1 knot.

Southern Ocean, to 40ºS, winds and current are discussed under the section South Africa to Southern Australia.

TROPICAL STORMS AND CYCLONES

Tropical Storms and Cyclones generally breed in the vicinity of 7º of their respective hemispheres and tend to track NW in the Northern Hemisphere and SW in the Southern Hemisphere. The most destructive areas tend to be between 10º and 15º, however this is not always the case.

A Cyclone normally “dies” out when it is over a major landmass, the exception seems to be Northern Madagascar, in the limits of these notes. Often a Cyclone will dissipate over Northern Madagascar, only to intensify over the Mozambique Channel.

The SW Indian Ocean has the most Tropical Storms or Cyclones in the Indian Ocean – the average from weather charts appears to be 8 Tropical Storms and 4 Cyclones per year.

The Cyclone season is from mid November to April, with December to March generally the worst months. However, Cyclones have been known outside the “season”.

ARABIAN SEA AND BAY OF BENGAL

The SW Monsoon period extends from May to September, and the Cyclone season is from May to December. Northern Australia’s Cyclone season is the same as the south Indian Ocean.

The Intertropical Convergance Zone, or ITZC or the Doldrums, is usually situated around the Equator or just south of it for most of the year. Often, in the “Belt”, one will sometimes experience days of tropical thunderstorms with dramatic lightning displays.
Excerpts from Indian Ocean Crossing Notes - by Tony Herrick

• East Indian Ocean
  • The High Seas (METAREA) forecast for the Eastern Indian Ocean is published by the Australian Bureau of Meteorology. It is broadcast on HF/SSB frequencies by Australian Weather West (VMW) on a regular automated schedule. See their relevant website page for schedule and frequencies.
• West Indian Ocean
  • The South Africa Maritime Mobile Net relays weather information for this area - see Cruiser's Nets for details.
  • Cruising Connections Weather Comprehensive weather links for SE Indian Ocean

Charts

Chart details?

References

• Southern Indian Ocean Crossing Notes (East to West & W - E) by Tony Herrick

Forum Discussions

Links to discussion threads on the CruiserLog Forum.

External Links

• Cruising Connections - Durban. New & Used Charts, Cruising Guides, Pilots, flags, etc.

Personal Notes

Personal experiences?

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